The efficient usage of space is extremely important in the ability to control operating costs in a manufacturing facility. Many engineers have realized the need to carefully consider the optimal positioning of working stations in a production line. The ability to place such stations in a product line in close proximity allows managers to efficiently use the remaining floor space for other important functions, or alternatively eliminate the need for the additional overhead expense associated with extra floor space.
Many manufacturing facilities also are established in buildings with multiple operating levels or floors. In these facilities, the processing line may require the transportation of work pieces or articles in progress between the different levels/floors. While inclined conveyors have long been used to accomplish this task, they inefficiently occupy floor space that may be needed for another purpose.
Helical conveyors have been designed to transport articles within a compact vertical space. An example of such a conveyor is disclosed in U.S. Pat. No. 1,892,206 to Dietz. A rotary element with concave article grooves for maintaining article separation is disposed within a stationary helical track. The grooves are adapted to receive articles (in this case cans or bottles) for vertical transport. As the element rotates, the can slides along the helical track and thus is either raised or lowered within the groove as the application dictates.
Each concave groove on the rotary element of the Dietz conveyor surrounds substantially one-half of the can or bottle that is engaged. Accordingly, it can be visualized that this conveyor design does not accommodate the accumulation of cans or bottles along the helical track. More particularly, if the cans or bottles are stopped for accumulation, jamming of the rotary element would immediately occur as the grooves could not temporarily disengage the cans or bottles.
The ability to accumulate articles along the track of a helical conveyor is very beneficial in many manufacturing facilities. Commonly, different work stations may be shut down from time to time for emergency repair and for maintenance. Absent the ability to accumulate articles as they exit upstream processing machines, the entire production line must be stopped. This can be very costly when many different processing machines are utilized in the entire production line.
Helical conveyors have been proposed to accomplish both functions; that is simultaneously vertically convey and store or accumulate a substantial number of the articles. In effect, these conveyor/accumulator assemblies provide the advantage of transporting articles between different elevations in a compact space and functioning essentially as a storage unit by accumulating the articles during vertical transfer. An example of such a helical conveyor/accumulator is disclosed in U.S. Pat. No. 3,261,453 to Hirs. A rotary drum is disposed within a metal helical track and an elongated brush (or brushes) is mounted on the drum. Thus, as the drum rotates, the brush pushes articles along the track and thus elevates (or lowers) and stores the articles, as desired.
It can be appreciated that over time the bristles on the brushes tend to fray or flatten, reducing their effectiveness and thus requiring periodic replacement. In addition, the bristles may hold and accumulate oil or debris, also reducing transporting efficiency. Further, the metallic nature of the track introduces the chance of the article being scratched or nicked. This is particularly undesirable when the conveyed articles are bearings or the like that have precise tolerances and exacting finishes.
Accordingly, there is a need to provide a device that can both vertically transport articles and, when conditions dictate the need, accumulate articles for temporary storage. Such a helical conveyor/accumulator would provide substantially frictionless surfaces for article contact to facilitate efficient conveyance and reduce the chances of article damage. As an additional advantage, upon release from accumulation, the helical conveyor/accumulator would allow a metered discharge. The conveyor/accumulator would also provide a helical track that is much easier to make and assemble than the prior art metal tracks. The conveyor/accumulator would be designed for long service life with minimal maintenance requirements.